A professor I admire once said — while discussing the films of Yasujiro Ozu, or maybe it was semiotics (can’t remember) — that watching the sun set can be both a thing of incredible beauty and deep sadness, often simultaneously. I thought of this as I watched Richard Linklater’s Before Midnight, which includes a scene of a couple sitting by the sea in Greece, watching the sun slowly dip below the horizon. It’s there, there, there — and then it’s not there. A fleeting flare of arresting orange. Present and then absent. Perhaps the beauty and sadness of a sunset has to do with the fact that it’s the process in nature we humans most identify with. Ours is a context of ephemerality.

Midnight just released in theaters, and it is certainly one of the best films of 2013 so far. But before you see it, be sure to watch the two preceding films in Linklater’s Before series: Before Sunrise (1995) and Before Sunset (2004). Together they comprise a trilogy that is one of the most understated and elegant in the history of cinema.

Linklater’s films follow the love story between Jesse (Ethan Hawke) and Celine (Julie Delpy) as it plays out in more or less real time in one Vienna night in 1994 (Before Sunrise), a sunset stroll in 2003 Paris (Before Sunset), and an evening jaunt in Greece in 2012 (Midnight). The films let us peek in on these two lives every nine years, witnessing only as much of their “present” as the 90-100 minutes of movie watching allows us to see. The glimpses we get into this couple’s journey together are snapshots not just of their particular world — compellingly characterized by highbrow garrulity, philosophizing and Gen X angst — but of humanity in general: how we age, how we love, how we fight and how we dream.

Similar in many ways to what Linklater, Hawke and Delpy are exploring in the Before series is what Michael Apted has done and is doing with the astonishing Up series. Beginning in 1964 as a British television documentary examining the lives of fourteen 7-year-old children representing a diverse array of socioeconomic positions in 1960s Britain, the Up series has followed its real-life characters every seven years since. 14 Up (1970) checked in on the children at age 14; 21 Up (1977) updated audiences on their lives as they each turned 21; and so on.56 Up just came out a few months ago and is now available to watch on Netflix, as are all of the other Up films.

In his review of 56 Up, the late Roger Ebert — who once called the Up series “the noblest project in cinema history” — wrote this: “It is a mystery, this business of life. I can’t think of any other cinematic undertaking that allows us to realize that more deeply.”

Indeed, I think that one of the great potentials of cinema — particularly when it is used in the way Linklater and Apted are using it in their respective series — is that it can capture some of the idiosyncrasies and mysteries of the “business of life” that we might otherwise fail to see (presumably because we are too busy wading through our own “business of life”). Things like the peculiar experience of the passage of time: simultaneously the most obvious and yet ungraspable mystery of existence.

The Before series is about love and relationships on one level, to be sure. But the real subject of these films is time, and the frequency with which it is discussed by the characters in the films hammers home that point.

“O let not Time deceive you, You cannot conquer Time,” says Jesse (Hawke) in Before Sunrise, quoting Dylan Thomas quoting W.H. Auden. At other times Jesse waxes philosophical about how surreal it is to self-consciously observe himself living in real time, or Celine shares about how she always feels like her life is either a dream of the future or a memory of the past. Meanwhile, the couple walks and talks in (more or less) real time, as the sun — that most vivid of all reminders of temporality — either rises, sets, or cedes its position to the moon. As Hawke said earlier this year when Midnight premiered at Sundance, the star of the Before series “is not Julie or [Hawke] but Father Time himself.”

The Up series is far less meta in its treatment of time; yet like the Beforefilms, Father Time is a palpable presence in every frame. There’s something compelling about observing the passage of time — 56 years, in this case — as it molds, batters, refines and weathers these people on each of their wildly divergent paths. Some of the original fourteen children grew up to be very successful; others not so much. Most started families and now have kids, grandkids, stepkids, and exes. Some (but not all) exceeded the expectations of the social class into which they were born. Some are happier than others (from what we can tell in our peeks inside, at least), and the only thing they all have in common is that none, not a one, has conquered time. They are all aging, and with every passing Up film we feel the weight of this ever more.

Cinema is unique among mediums in its ability to “sculpt in time,” as Andrey Tarkovsky wrote. It’s all about compressing, elongating, speeding up, and editing time to tell a story (that may span millennia or minutes) in the span of just a few hours. But Before and Up are especially compelling because rather than focusing on the filmmaker’s power over time, they focus on time’s power over us. Linklater tries his best to tell each Before film in real time, avoiding cinema’s manipulative power and instead foregrounding the somewhat eerie feeling of just sitting with time as it unfolds.

The Up films leverage cinema’s ability to compress time by including footage from the previous entries in each present portrait. What we get is essentially a moving-image scrapbook of each of these peoples’ 56-years, summarized in about ten minutes each. Watching it evokes the emotions of looking through an old box of photos and reliving an entire past in one quick burst of nostalgia. It confronts us with the expansiveness of what has come before; which seems large to us because our memories are painfully small and cannot hold every special moment we’ve had or beautiful thing we’ve seen, let alone the histories of other lives and lands.

Unless we have cameras there to capture every moment, our pasts are just as inaccessible to us as our futures. Memories, photos, tales of old can only reconstruct former glories up to a point (for a smart take on all this as it relates to “documenting” one’s past, see Sarah Polley’s amazing new film, Stories We Tell). And yet it could be argued that the “present” is the most elusive of all. For in reality, what we think of as the present is really just our brain processing things in the past — even if just a millisecond ago. Time is most relentless in the present because try as we might to slow it down or speed it up, it only goes by its own pace. The past and future are more malleable categories because they exist entirely in our minds, where we can elongate, embellish, or edit our recollection or vision of an experience, to our liking.

Tarkovsky puts it well in this excerpt from Sculpting In Time:

“Time is said to be irreversible. And this is true enough in the sense that ‘you can’t bring back the past’. But what exactly is this ‘past’? Is it what has passed? And what does ‘passed’ mean for a person when for each of us the past is the bearer of all that is constant in the reality of the present, of each current moment? In a certain sense the past is far more real, or at any rate more stable, more resilient than the present. The present slips and vanishes like sand between the fingers, acquiring material weight only in its recollection.”

The Before and Up films are powerful because they embody the “sand between the fingers” brevity of the present: reminding us that even the most magical moments in life are fleeting, that our “when I grow up” dreams will be here and gone before we know it, and that as a result it makes little sense to live in search of a permanent state of pleasure or satisfaction. Such a thing would be, as Solomon might say, like “chasing after the wind.” Our hearts will be restless, said Augustine, until they rest in Thee. And perhaps that is “Father” Time’s greatest gift to us: stirring up a restlessness in our souls that directs our longing to something Other, unfathomably infinite and unbound by time.